2017 Student Growth Percentiles

The visual below shows the percentage of students making typical or high growth by grade and subject, using student growth results from GADOE. Use the filter on the left to choose a different school or district, or the tabs at the top to switch to high school or district-level views.

In this example we can see that Brandon Elementary School shows progress at rates above the state average. An area of strength for Brandon in 2017 was 5th grade math, where 91% of students had typical or high growth. An area for reflection is 4th grade English- 66% of students achieved typical or high growth in 2017, which is about the state average, but a decline from 2016 when 83% of students achieved typical or high growth.

This visual is helpful for schools or districts to use root-cause analysis. Working with other school or district leaders, identify which grade/subject combinations are high or low-performing, or have seen significant change. Then discuss the causes of those notable data points, and how that information can be used for future improvement.

The Georgia Department of Education (GADOE) calculates Student Growth Percentiles (SGP) for students who take the Milestones exams. SGPs indicate how much a student’s achievement grew compared to academically similar peers. To calculate a 2017 SGP score, a student is grouped with other students with similar 2016 and 2015 scores, and then given a percentile rank based on how their 2016 score compares.

GADOE then uses SGP data to find the percentage of students making typical or high growth by school and district. “Typical or high growth” is defined as an SGP of at least 35. The state average percentage of students making typical or high growth is about 65% (100 – 35).

The SGP results displayed here include confidence intervals because the SGP calculation is a statistical estimate. Confidence intervals1 are displayed as blue bands. Similar to the margin of error in a poll, the confidence interval tells us the range of possible values, but the middle value is most likely. Schools or districts with few students will have wide confidence intervals; large schools and districts have more precise growth estimates so their confidence intervals will be smaller.

The typical or high growth calculation is also used to determine progress points on the CCRPI. However, the CCRPI only includes “full academic year” students, while the SGP data files include all tested students. The results used for CCRPI progress points might vary from the SGP files by a few points but they tend to show the same trends.

(1) Confidence intervals are calculated at the 95% level using the standard error of the sample mean. This is only one of two sources of uncertainty. Each student SGP score is also an estimate and has associated uncertainty, but is not available to us. Hence, the confidence intervals are an underestimate of the total uncertainty. We compensate for this by using a relatively large confidence interval- 95%.